Identification and molecular characterization of a trans-acting small interfering RNA producing locus regulating leaf rust responsive gene expression in wheat (Triticum aestivum L.)

Abstract

A novel leaf rust responsive ta-siRNA-producing locus was identified in wheat showing similarity to 28S rRNA and generated four differentially expressing ta-siRNAs by phasing which targeted stress responsive genes. Trans-acting-small interfering RNAs (Ta-siRNAs) are plant specific molecules generally involved in development and are also stress responsive. Ta-siRNAs identified in wheat till date are all responsive to abiotic stress only. Wheat cultivation is severely affected by rusts and leaf rust particularly affects grain filling. This study reports a novel ta-siRNA producing locus (TAS) in wheat which is a segment of 28S ribosomal RNA but shows differential expression during leaf rust infestation. Four small RNA libraries prepared from wheat Near Isogenic Lines were treated with leaf rust pathogen and compared with untreated controls. A TAS with the ability to generate four ta-siRNAs by phasing events was identified along with the microRNA TamiR16 as the phase initiator. The targets of the ta-siRNAs included α-gliadin, leucine rich repeat, trans-membrane proteins, glutathione-S-transferase, and fatty acid desaturase among others, which are either stress responsive genes or are essential for normal growth and development of plants. Expression of the TAS, its generated ta-siRNAs, and their target genes were profiled at five different time points after pathogen inoculation of susceptible and resistant wheat isolines and compared with mock-inoculated controls. Comparative analysis of expression unveiled differential and reciprocal relationship as well as discrete patterns between susceptible and resistant isolines. The expression profiles of the target genes of the identified ta-siRNAs advocate more towards effector triggered susceptibility favouring pathogenesis. The study helps in discerning the functions of wheat genes regulated by ta-siRNAs in response to leaf rust.

Harnessing genetic resistance to rusts in wheat and integrated rust management methods to develop more durable resistant cultivars

“…This shows that non-conserved miRNAs, which control disease resistance genes in gymnosperms and angiosperms, display fast flexibility in sequence variants, gene copy number, functions, and expression level (Zhang et al, 2019). Trans-acting-small interfering RNAs (Ta-siRNAs) were also found in wheat (Dutta et al, 2017). Comparative expression analysis of TAS, ta-siRNAs, and their target genes showed a differential and reciprocal relationship as well as discrete patterns between resistant and susceptible near-isogenic lines.…”

“…Comparative expression analysis of TAS, ta-siRNAs, and their target genes showed a differential and reciprocal relationship as well as discrete patterns between resistant and susceptible near-isogenic lines. The expression profiles of the target genes of the identified ta-siRNAs advocate more towards ETS favoring pathogenesis (Dutta et al, 2017). However, the mechanisms by which ta-siRNAs influences pathogenesis remains a mystery.…”

Application of small RNAs for plant protection

“…С открытием данного явления появился такой термин, как транс-действующая малая интерферирующая РНК (trans-acting small interfering RNAs -tasiРНК). TasiРНК не всегда имеет идеальное соответствие последовательностям целевых генов и, по-видимому, один вид tasiРНК может подавлять экспрессию нескольких генов [29].…”

“…Dutta и соавт. [29] описали в пшенице новый локус, продуцирующий tasiРНК (tasiRNA producing locus -TAS) при заражении растения стеблевой ржавчиной. Данный локус способен генерировать четыре вида малых РНК, которые в свою очередь действуют на α-глиадин, лейцин-богатый повтор (leucine-rich repeat -LRR), трансмембранные белки, глутатион-S-трансферазу (glutathione S-trans ferase -GST) и десатуразы жирных кислот, синтезируемые во время стресса и необходимые для нормального роста и развития растений.…”

“…Данный локус способен генерировать четыре вида малых РНК, которые в свою очередь действуют на α-глиадин, лейцин-богатый повтор (leucine-rich repeat -LRR), трансмембранные белки, глутатион-S-трансферазу (glutathione S-trans ferase -GST) и десатуразы жирных кислот, синтезируемые во время стресса и необходимые для нормального роста и развития растений. Белок α-глиадин влияет на прорастание зерен пшеницы и рост проростков, и при его отсутствии происходит заметное ухудшение качества белка [29,54].…”