Wheat grain preharvest sprouting and late maturity alpha-amylase

Abstract

Preharvest sprouting (PHS) and late maturity α-amylase (LMA) are the two major causes of unacceptably high levels of α-amylase in ripe wheat grain. High α-amylase activity in harvested grain results in substantially lower prices for wheat growers and at least in the case of PHS, is associated with adverse effects on the quality of a range of end-products and loss of viability during storage. The high levels of α-amylase are reflected in low falling number, the internationally accepted measure for grain receival and trade. Given the significant losses that can occur, elimination of these defects remains a major focus for wheat breeding programs in many parts of the world. In addition, the genetic, biochemical and molecular mechanisms involved in the control of PHS and LMA as well as the interactions with environmental factors have attracted a sustained research interest. PHS and LMA are independent, genetically controlled traits that are strongly influenced by the environment, where the effects of particular environmental factors vary substantially depending on the stage of grain development and ripening. This review is a summary and an assessment of results of recent research on these important grain quality defects.

Differential incidence of the lemma on seed germination among different Paspalum dilatatum genotypes

“…Both in domesticated and wild grass species, non-dormant genotypes or seeds with lowered seed dormancy -achieved by stratification or afterripening -exhibit a higher germination response to increasing exogenous ABA levels, i.e. less sensitivity to ABA (Romagosa et al, 2001;Gianinetti and Vernieri, 2007;Goggin et al, 2009;Mares and Mrva, 2014). Thus, ABA sensitivity could be assayed to compare levels of seed dormancy, specifically at the caryopsis or embryo level.…”

Impact of Growth Habit and Architecture Genes on Adaptation and Performance of Bread Wheat

“…This could contribute to reducing the worldwide physiological phenomenon of preharvest sprouting (PHS). Preharvest sprouting, which is the germination of seed grains in the mother ear before harvest due to humid conditions, is prevalent in wheat-growing regions experiencing high rainfall during the period of grain maturity and ripening [90]. This results in significant losses in the wheat production industry such as the downgrading of premium milling quality wheat to feed quality [91].…”

Approaches to improve wheat grain quality: breeding for falling number

“…В годы с неблагоприятной погодой (дожди, росы, холод) в период налива зерна и уборки урожая страдают и мно-гие краснозерные сорта, для этого достаточно небольшого количества осадков (около 10-15 мм), особенно при медленном их выпадении (Mares, Mrva, 2014). Симпто-мы прорастания -разрыв оболочки в области зародыша, сморщивание и обесцвечивание семени, а затем появление корешка и побега.…”

“…В регулировании покоя семян важную роль играют транскрипционные факторы, абсцизовая кислота (АБК), гиббереллин (ГК), жасмонат и другие гормоны Jacobsen et al, 2013). Ключевым детерминантом покоя является AБК, роль этого и других гормонов в УкПП нуждается в дальнейшем изучении (Kondhare et al, 2012;Mares, Mrva, 2014).…”

“…Генетиче-ский контроль LMA не зависит от генетического контроля обычного ПП, вызванного дождливой погодой (Flintham et al, 2011;Mares, Mrva, 2014), хотя встречаются случаи ассоциации QTLs, контролирующих LMA и ПП.…”