Becker Rafael, Farias-Singer Rosana, Gurvich Diego E, Pittella Renan, Calderon-Quispe Fernando H, de Moraes Brandalise Júlia, Singer Rodrigo Bustos
Graduate Program in Botany (PPGBOT-UFRGS), Universidade Federal do Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil.
Porto Alegre Botanical Garden, Secretaria do Meio Ambiente e Infraestrutura do Estado do Rio Grande do Sul, Porto Alegre 90119-900, RS, Brazil.
Plants (Basel). 2024 Oct 15;13(20):2890. doi: 10.3390/plants13202890.
All 32 Brazilian species of Speg (Cactaceae) occurring in Rio Grande do Sul State are considered threatened, according to the IUCN criteria. Until 2021, (CR) was known by only two small populations. However, a new population with over 400 individuals was discovered in 2021, prompting the study of its reproductive biology as a way to promote its conservation. Anthesis, breeding system, and natural pollination were studied in the field. The breeding system was studied by applying controlled pollination treatments to plants excluded from pollinators (bagged). Germination features were studied at the Seed Bank of the Porto Alegre Botanical Garden under controlled temperatures (20, 25, and 30 °C). The anthesis is diurnal and lasts for up to four days. The flowers offer pollen as the sole resource to the pollinators. The study species is unable to set fruit and seed without the agency of pollinators and has self-incompatible (unable to set fruit and seeds when pollinated with pollen of the same individual) characteristics that can considerably restrict its reproduction. Native bees of Halictidae and Apidae (Hymenoptera) are the main pollinators, with a smaller contribution of Melyridae (Coleoptera) and Syrphidae (Diptera). Natural fruit set is moderate (≤64%, per individual), but the species presents vegetative growth, producing several branches from the mother plant. Seeds showed the optimum germination rate at 20 °C and an inhibition of 75% in germinability at 30 °C. Our findings suggest the need to manage the species' habitat to guarantee the permanency of the plants and healthy populations of pollinators as well. Our findings raise concerns about the germination and establishment of new individuals in the context of rising temperatures caused by climate change. Suggestions for the possible management of the extant populations are made.
根据世界自然保护联盟（IUCN）的标准，南里奥格兰德州出现的所有32种巴西斯佩格仙人掌属（仙人掌科）植物均被视为受到威胁。直到2021年，极度濒危（CR）等级的物种仅知有两个小种群。然而，2021年发现了一个有400多个个体的新种群，促使人们对其生殖生物学进行研究，以此作为促进其保护的一种方式。在野外研究了开花期、繁殖系统和自然授粉情况。通过对排除传粉者的植株（套袋）进行控制授粉处理来研究繁殖系统。在阿雷格里港植物园种子库中，在控制温度（20、25和30℃）下研究发芽特性。花期为昼间开放，持续长达四天。花朵为传粉者提供花粉作为唯一资源。研究的物种在没有传粉者的情况下无法结果和结籽，并且具有自交不亲和（用同一个体的花粉授粉时无法结果和结籽）的特征，这会严重限制其繁殖。隧蜂科和蜜蜂科（膜翅目）的本地蜜蜂是主要传粉者，拟花萤科（鞘翅目）和食蚜蝇科（双翅目）的贡献较小。自然坐果率中等（每个个体≤64%），但该物种呈现营养生长，从母株上长出多个分支。种子在20℃时发芽率最佳，在30℃时发芽能力受到75%的抑制。我们的研究结果表明，需要管理该物种的栖息地，以确保植物的持久性以及传粉者的健康种群。我们的研究结果引发了人们对气候变化导致气温上升背景下新个体发芽和定植的担忧。针对现存种群的可能管理提出了建议。
