News Update on Fruit Crops : May 21

[1] Comparative mapping and marker-assisted selection in Rosaceae fruit crops

The development of saturated linkage maps using transferable markers, restriction fragment length polymorphisms, and micro-satellites has provided a foundation for fruit tree genetics and breeding. A Prunus reference map with 562 such markers is available, and a further set of 13 maps constructed with a subset of these markers has allowed genome comparison among seven Prunus diploid (x = 8) species (almond, peach, apricot, cherry, Prunus ferganensis, Prunus davidiana, and Prunus cerasifera); marker colinearity was the rule with all of them. Preliminary results of the comparison between apple and Prunus maps suggest a high level of synteny between these two genera. Conserved genomic regions have also been detected between Prunus and Arabidopsis. By using the data from different linkage maps anchored with the reference Prunus map, it has been possible to establish, in a general map, the position of 28 major genes affecting agronomic characters found in different species. Markers tightly linked to the major genes responsible for the expression of important traits (disease/pest resistances, fruit/nut quality, self-incompatibility, etc.) have been developed in apple and Prunus and are currently in use for marker-assisted selection in breeding programs. Quantitative character dissection using linkage maps and candidate gene approaches has already started. Genomic tools such as the Prunus physical map, large EST collections in both Prunus and Malus, and the establishment of the map position of high numbers of ESTs are required for a better understanding of the Rosaceae genome and to foster additional research and applications on fruit tree genetics.

[2] Doubled haploid production in fruit crops

The interest of fruit breeders in haploids and doubled haploids (DH), lies in the possibility of shortening the time needed to produce homozygous lines compared to conventional breeding. Haplo-diploidization through gametic embryogenesis allows single-step development of complete homozygous lines from heterozygous parents. In a conventional breeding programme, a pure line is developed after several generations of selfing. With fruit crops, characterized by a long reproductive cycle, a high degree of heterozygosity, large size, and, sometimes, self-incompatibility, there is no way to obtain haploidization through conventional methods. This paper reviews the current status of research on doubled haploid production in the main fruit crops: Citrus, Malus domestica, Pyrus communis, Pyrus pyrifolia, Prunus persica, Prunus avium, Prunus domestica, Prunus armeniaca, Vitis vinifera, Actinidia deliciosa, Olea europaea, Morus alba, Actinidia deliziosa, [Musa balbisiana (BB)], Carica papaya, Annona squamosa, Feijoa sellowiana, Opuntia ficus-indica, Eriobotrya japonica.

[3] Diseases of fruit crops

Accounts are given of these diseases in India, on mango, banana, citrus, grapevine, guava, papaw, coconut palm, and pome and stone fruit, caused by fungi, bacteria, viruses, mycoplasma-like organisms, algae and nonparasitic agencies. Details include incidence, distribution, symptoms, aetiology, life cycle and control.

[4] Yield, Fruit Body Diameter and Cropping Duration of Oyster Mushroom (Pleurotus sajor caju) Grown on Different Grasses and Paddy Straw as Substrates

The present experiment aimed at finding the suitability of some grasses as cost effective alternative substrates, for cultivation of one species of oyster mushroom viz., Pleurotus sajor caju (Fr.) Singer in eastern India. Relative efficacy three grasses viz., kash grass (Saccharum spontaneum L.), sabai grass (Eulaliopsis binata C.E. Hubb (Retz.)) and lemon grass (Cymbopogon citrates Stapf.) was tested by using each of them either as whole substrate or in combination with the conventional substrate i.e., paddy straw in 3:1, 1:1, and 1:3 ratios. Results revealed that the maximum yield of mushroom was recorded under paddy straw with biological efficiency of 85.9%. However, no significant difference in yield was found when 25% or 50% of the conventional substrate (paddy straw) was replaced by lemon grass and sabai grass. The results indicated that grasses which are available in plenty in the forests and wastelands of lateritic uplands of eastern India can be utilized successfully as promising substrate for the commercial cultivation of Pleurotus sajor caju.

[5] Seasonal Crop Raiding of Fruit Trees by Asian Elephants: An Insight into Foraging Preferences from Croplands Abutting Bannerghatta National Park, Bengaluru, Karnataka, India

This study was undertaken to evaluate factors which potentially influence crop depredation by Asian elephants during the non-cropping season. The study was conducted in a 2.5 km zone abutting Bannerghatta Wildlife Range of Bannerghatta National Park, Karnataka. Three fruit trees which are commonly raided by elephants, namely jackfruit (Artocarpus heterophyllus), mango (Mangifera indica) and tamarind (Tamarindus indica) were selected for the study. The convenient sampling approach was adopted to map individual trees of the three species between May and July 2015. Factors such as the phenological stage, the parts of the tree foraged, the distance from the Park boundary and the crop clustering pattern were recorded. Among the 1368 mapped fruit trees, only 4.31% (n = 59) of the trees were found foraged on. However, 79.66% of the damage occurred in trees that were fruiting. There also seemed to be a preference in fruits foraged; A. heterophyllus had the highest damage (8.84%), followed by T. indica (4.20%) and M. indica (3.66%), and the preference ratios for the three species were estimated to be 2.05, 0.97 and 0.85, respectively. The analysis showed that the spatial foraging pattern was also species dependent, with damage in   A. heterophyllus and M. indica recorded at distances more than one km from the Park unlike in the case of T. indica. Refuge cover availability and forage quantity measured through clustering pattern, was not found to positively increase foraging preference. It was also observed that damage in fruiting M. indica were more common in areas which contained both A. heterophyllus and T. indica within 100 m, than areas which had either none or only one of the species present. Spatial analysis revealed a concentration of foraging in the north-western and south-eastern portions of the National Park. Results obtained in the study aided in identifying the indicative factors which influence the crop foraging pattern during the non-cropping season. A detailed long-term study on the foraging ecology of elephants in other human-dominated regions will help strategize effective human-elephant conflict mitigation measures.

Reference

[1] Dirlewanger, E., Graziano, E., Joobeur, T., Garriga-Calderé, F., Cosson, P., Howad, W. and Arús, P., 2004. Comparative mapping and marker-assisted selection in Rosaceae fruit crops. Proceedings of the national academy of sciences101(26), pp.9891-9896.

[2] Germana, M.A., 2006. Doubled haploid production in fruit crops. Plant Cell, Tissue and Organ Culture86(2), pp.131-146.

[3] Pathak, V.N., 1980. Diseases of fruit crops. Diseases of fruit crops.

[4] Rajak, S., Mahapatra, S.C. and Basu, M., 2011. Yield, fruit body diameter and cropping duration of oyster mushroom (Pleurotus sajor caju) grown on different grasses and paddy straw as substrates. European Journal of Medicinal Plants, pp.10-17.

[5] Bantalpad, M., Gayathri, A. and Krishnan, A., 2017. Seasonal Crop Raiding of Fruit Trees by Asian Elephants: An Insight into Foraging Preferences from Croplands Abutting Bannerghatta National Park, Bengaluru, Karnataka, India. Asian Journal of Environment & Ecology, pp.1-12.

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