TY - JOUR

T1 - Occurrence of albinism during wheat androgenesis is correlated with repression of the key genes required for proper chloroplast biogenesis

AU - Canonge, Julie

AU - Roby, Charlotte

AU - Hamon, Céline

AU - Potin, Philippe

AU - Pfannschmidt, Thomas

AU - Philippot, Murielle

N1 - Funding Information: This work was supported by the European Regional Development Fund and by the Ministry of Higher Education, Research and Innovation in the context of the CIFRE PhD thesis no. 2017/0173 funded by ANRT, and by SECOBRA Recherches.

PY - 2021/11/17

Y1 - 2021/11/17

N2 - Main conclusion: The phenomenon of albinism in wheat androgenesis is linked to the transcriptional repression of specific genes involved in chloroplast biogenesis during the first weeks of in vitro culture. Abstract: Isolated microspore culture is widely used to accelerate breeding programs and produce new cultivars. However, in cereals and particularly in wheat, the use of this technique is limited due to the high proportion of regenerated albino plantlets. The causes and mechanisms leading to the formation of albino plantlets in wheat remain largely unknown and, to date, no concrete solution has been found to make it possible to overcome this barrier. We performed a molecular study of proplastid-to-chloroplast differentiation within wheat microspore cultures by analyzing the expression of 20 genes specifically involved in chloroplast biogenesis. Their expression levels were compared between two wheat genotypes that exhibit differential capacities to regenerate green plantlets, i.e., Pavon and Paledor, which produce high and low rates of green plants, respectively. We observed that chloroplast biogenesis within wheat microspores was affected as of the very early stages of the androgenesis process. A successful transition from a NEP- to a PEP-dependent transcription during early plastid development was found to be strongly correlated with the formation of green plantlets, while failure of this transition was strongly correlated with the regeneration of albino plantlets. The very low expression of plastid-encoded 16S and 23S rRNAs within plastids of the recalcitrant genotype Paledor suggests a low translation activity in albino plastids. Furthermore, a delay in the activation of the transcription of nuclear encoded key genes like GLK1 related to chloroplast biogenesis was observed in multicellular structures and pro-embryos of the genotype Paledor. These data help to understand the phenomenon of albinism in wheat androgenesis, which appears to be linked to the transcriptional activation of specific genes involved in the initial steps of chloroplast biogenesis that occurs between days 7 and 21 of in vitro culture.

AB - Main conclusion: The phenomenon of albinism in wheat androgenesis is linked to the transcriptional repression of specific genes involved in chloroplast biogenesis during the first weeks of in vitro culture. Abstract: Isolated microspore culture is widely used to accelerate breeding programs and produce new cultivars. However, in cereals and particularly in wheat, the use of this technique is limited due to the high proportion of regenerated albino plantlets. The causes and mechanisms leading to the formation of albino plantlets in wheat remain largely unknown and, to date, no concrete solution has been found to make it possible to overcome this barrier. We performed a molecular study of proplastid-to-chloroplast differentiation within wheat microspore cultures by analyzing the expression of 20 genes specifically involved in chloroplast biogenesis. Their expression levels were compared between two wheat genotypes that exhibit differential capacities to regenerate green plantlets, i.e., Pavon and Paledor, which produce high and low rates of green plants, respectively. We observed that chloroplast biogenesis within wheat microspores was affected as of the very early stages of the androgenesis process. A successful transition from a NEP- to a PEP-dependent transcription during early plastid development was found to be strongly correlated with the formation of green plantlets, while failure of this transition was strongly correlated with the regeneration of albino plantlets. The very low expression of plastid-encoded 16S and 23S rRNAs within plastids of the recalcitrant genotype Paledor suggests a low translation activity in albino plastids. Furthermore, a delay in the activation of the transcription of nuclear encoded key genes like GLK1 related to chloroplast biogenesis was observed in multicellular structures and pro-embryos of the genotype Paledor. These data help to understand the phenomenon of albinism in wheat androgenesis, which appears to be linked to the transcriptional activation of specific genes involved in the initial steps of chloroplast biogenesis that occurs between days 7 and 21 of in vitro culture.

KW - Albinism

KW - Chloroplast biogenesis

KW - Microspore culture

KW - Targeted transcriptomic study

KW - Triticum aestivum L

UR - http://www.scopus.com/inward/record.url?scp=85119143932&partnerID=8YFLogxK

U2 - 10.1007/s00425-021-03773-3

DO - 10.1007/s00425-021-03773-3

M3 - Article

C2 - 34786602

AN - SCOPUS:85119143932

VL - 254

JO - Planta

JF - Planta

SN - 0032-0935

IS - 6

M1 - 123

ER -