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Aluminum‐dependent stoppage of root growth requires the DNA damage response (DDR) pathway including the p53‐like transcription factor SUPPRESSOR OF GAMMA RADIATION 1 (SOG1), which promotes terminal differentiation of the root tip in response to Al dependent cell death. Transcriptomic analyses identified Al‐induced SOG1‐regulated targets as candidate mediators of this growth arrest. Analysis of these factors either as loss‐of‐function mutants or by overexpression in the als3‐1 background shows ERF115, which is a key transcription factor that in other scenarios is rate‐limiting for damaged stem cell replenishment, instead participates in transition from an actively growing root to one that has terminally differentiated in response to Al toxicity. This is supported by a loss‐of‐function erf115 mutant raising the threshold of Al required to promote terminal differentiation of Al hypersensitive als3‐1. Consistent with its key role in stoppage of root growth, a putative ERF115 barley ortholog is also upregulated following Al exposure, suggesting a conserved role for this ATR‐dependent pathway in Al response. In contrast to other DNA damage agents, these results show that ERF115 and likely related family members are important determinants of terminal differentiation of the root tip following Al exposure and central outputs of the SOG1‐mediated pathway in Al response. Summary Statement: Aluminum dependent stoppage of root growth in Arabidopsis thaliana requires a SUPPRESSOR OF GAMMA RADIATION 1 controlled transcriptional program that includes ERF115 and family members. Loss of ERF114 and ERF115 results in prevention of the severe response to Al normally seen in the Al hyperresponsive mutant als3‐1. [ABSTRACT FROM AUTHOR]

High frequency of albino plant formation in isolated microspore or anther cultures is a great problem limiting the possibility of their exploitation on a wider scale. It is highly inconvenient as androgenesis-based doubled haploid (DH) technology provides the simplest and shortest way to total homozygosity, highly valued by plant geneticists, biotechnologists and especially, plant breeders, and this phenomenon constitutes a serious limitation of these otherwise powerful tools. The genotype-dependent tendency toward albino plant formation is typical for many monocotyledonous plants, including cereals like wheat, barley, rice, triticale, oat and rye - the most important from the economical point of view. Despite many efforts, the precise mechanism underlying chlorophyll deficiency has not yet been elucidated. In this chapter, we review the data concerning molecular and physiological control over proper/disturbed chloroplast biogenesis, old hypotheses explaining the mechanism of chlorophyll deficiency, and recent studies which shed new light on this phenomenon., (© 2021. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

TILLING (Targeting Induced Local Lesions IN Genomes) is a strategy used for functional analysis of genes that combines the classical mutagenesis and a rapid, high-throughput identification of mutations within a gene of interest. TILLING has been initially developed as a discovery platform for functional genomics, but soon it has become a valuable tool in development of desired alleles for crop breeding, alternative to transgenic approach. Here we present the Hor TILLUS ( Hor deum - TILL ING- U niversity of S ilesia) population created for spring barley cultivar "Sebastian" after double-treatment of seeds with two chemical mutagens: sodium azide (NaN 3 ) and N-methyl-N-nitrosourea (MNU). The population comprises more than 9,600 M 2 plants from which DNA was isolated, seeds harvested, vacuum-packed, and deposited in seed bank. M 3 progeny of 3,481 M 2 individuals was grown in the field and phenotyped. The screening for mutations was performed for 32 genes related to different aspects of plant growth and development. For each gene fragment, 3,072-6,912 M 2 plants were used for mutation identification using LI-COR sequencer. In total, 382 mutations were found in 182.2 Mb screened. The average mutation density in the Hor TILLUS, estimated as 1 mutation per 477 kb, is among the highest mutation densities reported for barley. The majority of mutations were G/C to A/T transitions, however about 8% transversions were also detected. Sixty-one percent of mutations found in coding regions were missense, 37.5% silent and 1.1% nonsense. In each gene, the missense mutations with a potential effect on protein function were identified. The Hor TILLUS platform is the largest of the TILLING populations reported for barley and best characterized. The population proved to be a useful tool, both in functional genomic studies and in forward selection of barley mutants with required phenotypic changes. We are constantly renewing the Hor TILLUS population, which makes it a permanent source of new mutations. We offer the usage of this valuable resource to the interested barley researchers on cooperative basis.