Variation in pollen viability among Leptochloa crinita accessions: implications for directed crosses

ABSTRACT

Leptochloa crinita, a native forage grass from American arid regions, is widely used for range grazing and revegetation of degraded lands. Despite its importance, progress in breeding and genetic research has been hindered by the difficulty of achieving sexual crosses between L. crinita plants. We hypothesize that factors associated with pollen quality can influence the effectiveness of directed sexual crosses in this species. Thus, the present study investigated pollen viability and longevity in a genetically diverse collection of 21 L. crinita accessions. Pollen viability was estimated at 0, 30, 60, and 180 minutes after anthers dehiscence (MAAD) by two methods: 1) acetocarmine staining; and 2) in vitro germination of pollen grains in culture media containing 0.4-1.0 M sucrose. The staining method overestimated pollen viability, whereas the in vitro germination assay provided accurate and reliable estimates, being 0.6 M the optimal sucrose concentration in the medium, in terms of germination rates and discriminatory power among the accessions. In all the accessions, pollen viability was highest at 0-30 MAAD, and decayed very rapidly, to reach levels below 5% at 180 MAAD. Significant (p<0.05) and broad variation for pollen viability was found among the accessions, with mean values in the range of 49-89% (0 MAAD), 32-76% (30 MAAD), 24-45% (60 MAAD), and 0.6-4.9% (180 MAAD), allowing the identification of six accessions exhibiting the greatest pollen viabilities. These results suggest 0-30 MAAD and using the selected (best) pollen donors, on emasculated female parentals, as the optimal conditions for attempting sexual crosses in L. crinita.

KEYWORDS:

• Leptochloa crinita
• sexual reproduction
• pollen viability
• pollen germination
• pollen longevity

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/23818107.2024.2365844.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

DELD, PCK, JBC, and PFC conceptualized and designed the experiments; DELD and MMR performed the experiments; DELD and SC analyzed the data; DELD wrote the manuscript draft; PFC, DELD, and PCK revised the manuscript and prepared final version. All authors read and approved the final manuscript.

Data availability statement

The research data used to support the findings of this study are available from the corresponding author upon request.

Additional information

Funding

This research was funded by the ‘Agencia Nacional de Promoción Científica y Tecnológica’ through grant [PICT-2021-I-A-00521], and by the National University of Cuyo (Mendoza, Argentina) through grant ‘[SIIP Tipo 1 Bienal 2022 0010-T1]’. DELD and SC were supported by the Argentine National Council of Scientific and Technical Research (CONICET) doctoral fellowships.