Teliospore germination and nuclear behavior of Puccinia rutainsulara, a microcyclic Hawaiian rust

Abstract

Puccinia rutainsulara recently was described as a microcyclic rust on Melicope (= Pelea) spp. (Rutaceae) endemic to Hawaii. Spermogonia are not produced, and teliospores are extruded from deep-seated telia in tightly compacted bristle-like columns. Teliospores produced an elongate basidium, typically with one, but rarely two, basidiospores. Following karyogamy, the nucleus migrated into the basidium and divided one or more times to produce variably two, three, or four daughter nuclei. While the other nuclei remained apparently functionless in the basidium, the distal-most nucleus migrated into the developing basidiospore and divided to produce a tetranucleate basidiospore. The observed nuclear behavior and production of a single basidiospore are not typical of rust fungi elsewhere, but similar unusual teliospore germination and nuclear behavior have been observed in other Hawaiian rusts.

Key Words:

• Hawaiian rusts
• nuclear behavior
• teliospore germination