GENETIC AND PHYSIOLOGICAL ASPECTS OF SILIQUE SHATTERING IN RAPESEED AND MUSTARD

Abstract

Rapeseed (Brassica napus L.) and mustard (Brassica juncea L.) are two important oilseed crops grown worldwide for edible oil and meal production, as well as, a source of renewable energy. Silique shattering at the maturity stage is the major cause of seed yield reduction in brassica. Losses in seed yield are more in developing countries due to poor management and the non-availability of combine harvesters. Silique shattering resistance is essential for achieving good seed yield especially in Brassica napus. The silique on plants of rapeseed and mustard mature in different phases due to indeterminate growth habit, which is also a reason for shattering losses. Silique shattering is linked with the creation of a dehiscence zone in a brassica pod. When the siliqua wall loses its hydration, along the length of the siliqua, a few cell layers separate the replum from the pericarp tip of the two silique valves. In the dehiscence zone, it involves the collapse of cell walls and cell separation, as well as, the destruction of the middle lamella and enhanced hydrolytic enzyme activity. To avoid seed yield losses, resistance against silique shattering is essential in rapeseed and mustard cultivars. There are multiple QTLs discovered that control variance in silique shattering. Previous studies validated the shattering process in the model plant Arabidopsis thaliana was controlled by eight different genes. However, their role in controlling silique shattering in rapeseed and mustard is unknown. Modern tools of mutation breeding and genetic engineering, especially CRISPR/Cas9 technology, can be utilized to identify the genetic source for shattering resistance in rapeseed and mustard, which will be helpful for the development of silique-shattering